Many passenger vehicles, tractor trailers, and other commercial vehicles are now equipped with crash data recorders, event data recorders, or other control modules, that store vehicle data electronically. These devices continually record vehicle parameters such as speed, throttle position, and braking, and are generally designed to lock the data in memory in the event of a crash. In most cases, we can retrieve information stored within the vehicle data recorder, and we can then analyse this data to determine how the vehicle was being operated in the moments prior to a collision. This information can be very helpful in reconstructing the collision, and understanding the driver’s actions leading up to the crash. Some of the data points logged in a crash data recorder may include:

• Airbag system warning lamp status (on / off)
• Driver restraint system status (buckled / unbuckled)
• Vehicle speed or impact speed change
• Percent throttle / engine speed
• Brake light switch circuit status (on / off)